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Keywords = Proteus mirabilis, MIC

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14 pages, 911 KB  
Communication
The Antibacterial Potential of Zn(II)–Cannabinoid Acid Equilibrium Systems Against Gram-Positive and Gram-Negative Microorganisms
by Magdalena Woźniczka, Weronika Gonciarz, Manas Sutradhar, Adília Januário Charmier, Susana Santos and Marek Pająk
Appl. Sci. 2026, 16(14), 7031; https://doi.org/10.3390/app16147031 - 13 Jul 2026
Viewed by 272
Abstract
Interest is growing in the antimicrobial potential of the non-psychoactive cannabinoids, such as cannabidiolic acid (CBDA) and cannabigerolic acid (CBGA), and their metal systems. The present study follows on from previous potentiometric and ESI-MS studies confirming the formation of stable zinc(II) species with [...] Read more.
Interest is growing in the antimicrobial potential of the non-psychoactive cannabinoids, such as cannabidiolic acid (CBDA) and cannabigerolic acid (CBGA), and their metal systems. The present study follows on from previous potentiometric and ESI-MS studies confirming the formation of stable zinc(II) species with cannabinoid acids in an alcohol–water environment under physiological conditions. The antibacterial action of the compounds was assessed against reference Gram-negative strains (Pseudomonas aeruginosa, Escherichia coli, Proteus mirabilis) and Gram-positive strains (Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis) using minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) assays. Their cytotoxicity was also evaluated in vitro using mouse fibroblasts. The tested compounds were found to demonstrate pronounced selectivity against Gram-positive bacterial strains compared to Gram-negative bacteria. The antibacterial efficacy of the free ligands was enhanced by the presence of Zn(II) in the solution: the equilibrium mixtures exhibited greater inhibitory activity against E. faecalis and S. epidermidis, with MIC and MBC values being non-cytotoxic toward L929 fibroblasts under the tested in vitro conditions. However, Gram-negative bacteria were only found to be susceptible at elevated concentrations, which also induced cytotoxic effects. Among the free ligands, CBGA exhibited slightly stronger antibacterial activity than CBDA. Full article
(This article belongs to the Special Issue Synthesis and Biological Evaluation of New Compounds)
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27 pages, 13773 KB  
Article
Antimicrobial Activity and Antibiotic Synergy of Saponin-Enriched Bark Extracts from Argania spinosa: Influence of Ecogeographical Origin
by Fatma Benlekhal, Ouahiba Moumen, Widad Hadjab, Adam Grzywaczyk, Wojciech Smułek, Urszula Guzik and Omar Kharoubi
Microbiol. Res. 2026, 17(6), 117; https://doi.org/10.3390/microbiolres17060117 - 22 Jun 2026
Viewed by 590
Abstract
Antimicrobial resistance represents a major global health challenge, highlighting the urgent need for alternative bioactive compounds from natural sources. This study investigated the phytochemical composition and antimicrobial potential of saponin-enriched extracts from the trunk bark of Argania spinosa (L.) Skeels, collected from two [...] Read more.
Antimicrobial resistance represents a major global health challenge, highlighting the urgent need for alternative bioactive compounds from natural sources. This study investigated the phytochemical composition and antimicrobial potential of saponin-enriched extracts from the trunk bark of Argania spinosa (L.) Skeels, collected from two contrasting Algerian regions: the coastal area of Stidia (ES) and the Saharan region of Tindouf (ET). Extraction yields were comparable (approximately 12.6%). UHPLC-MS analysis revealed distinct phytochemical profiles, with ES enriched in oleanane-type saponins and flavonoids, whereas ET showed a higher abundance of bayogenin-type derivatives. Key compounds included arganine C, E, and J, as well as catechin and quercetin. Antimicrobial activity was evaluated using agar well diffusion and broth microdilution assays against clinically relevant microorganisms, including the reference strains Staphylococcus aureus and Listeria innocua, together with Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, Proteus mirabilis, and Candida albicans. Both extracts exhibited broad-spectrum antimicrobial activity, although ES consistently showed lower Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal, Fungicidal Concentration (MBC)/(MFC) values than ET. MIC values ranged from 25 to 50 mg/mL for ES and from 50 to 100 mg/mL for ET. Synergistic interactions were observed between ES and gentamicin against S. aureus and between both extracts and kanamycin against K. pneumoniae. Membrane permeability assays demonstrated that both extracts increased bacterial membrane permeability, with ET producing a stronger permeabilizing effect. Atomic force microscopy of ES-treated cells revealed marked alterations in bacterial surface morphology, while molecular docking supported strong interactions of mi-saponin B and arganine derivatives with key bacterial targets. Collectively, these findings highlight the potential of A. spinosa bark saponins as natural antimicrobial agents and promising antibiotic adjuvants against multidrug-resistant pathogens. Full article
(This article belongs to the Section Antimicrobials and Antimicrobial Resistance)
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10 pages, 217 KB  
Article
Cefiderocol Is Effective In Vitro Against Numerous Gram-Negative Species Isolated from Keratitis Patients
by Jonathan B. Mandell, Robert M. Q. Shanks and Eric G. Romanowski
Antibiotics 2026, 15(4), 348; https://doi.org/10.3390/antibiotics15040348 - 29 Mar 2026
Cited by 1 | Viewed by 617
Abstract
Background: To evaluate the potential of cefiderocol as a topical ophthalmic antibiotic by determining the susceptibility of keratitis isolates from an extensive panel of Gram-negative bacterial species to this siderophore-cephalosporin class antibiotic. Methods: Minimum Inhibitory Concentrations (MICs) of cefiderocol were determined by the [...] Read more.
Background: To evaluate the potential of cefiderocol as a topical ophthalmic antibiotic by determining the susceptibility of keratitis isolates from an extensive panel of Gram-negative bacterial species to this siderophore-cephalosporin class antibiotic. Methods: Minimum Inhibitory Concentrations (MICs) of cefiderocol were determined by the broth dilution method using iron-depleted, cation-adjusted Mueller–Hinton broth. The following Gram-negative bacteria were included: Acinetobacter baumannii (n = 13), Achromobacter xylosoxidans (n = 14), Escherichia coli (n = 15), Klebsiella aerogenes (n = 14), Klebsiella pneumoniae (n = 13), Klebsiella oxytoca (n = 14), Moraxella spp. (n = 15), Proteus mirabilis (n = 13), Pseudomonas aeruginosa (n = 17), Serratia marcescens (n = 14) and Stenotrophomonas maltophilia (n = 12). MIC90 values were calculated for each of the species. Results: MIC90 values (µg/mL): A. baumannii (0.5), A. xylosoxidans (0.25), E. coli (0.5), K. aerogenes (1.0), K. oxytoca (0.5), K. pneumoniae (0.5), Moraxella spp. (0.5), P. mirabilis (0.25), P. aeruginosa (0.5), S. marcescens (0.5), and S. maltophilia (0.25). In total, 100% of the isolates were determined to be susceptible to cefiderocol in vitro except for A. xylosoxidans and Moraxella spp., for which there are no established breakpoints for cefiderocol. Conclusions: Cefiderocol demonstrated in vitro activity against the tested panel of Gram-negative keratitis isolates. The results of this study suggest cefiderocol may be useful for the treatment of keratitis caused by numerous Gram-negative pathogens. Further development of cefiderocol for the topical treatment of Gram-negative keratitis is indicated. Full article
(This article belongs to the Special Issue Antimicrobial Treatment and Antibiotic Use in Ophthalmology)
14 pages, 674 KB  
Review
Resistance of Uropathogens to Tebipenem: An Analysis of the Evidence from In Vitro Antimicrobial Susceptibility Studies
by Matthew E. Falagas, Christina-Maria Asimotou, Dimitrios S. Kontogiannis, Laura T. Romanos, Panagiota Poziou and Iva D. Tzvetanova
Microorganisms 2026, 14(3), 726; https://doi.org/10.3390/microorganisms14030726 - 23 Mar 2026
Viewed by 943
Abstract
Tebipenem is a new carbapenem antibiotic that binds to penicillin-binding proteins (PBPs). Given the need for effective antibiotics against multidrug-resistant (MDR) bacteria, this review evaluated the in vitro antimicrobial activity of tebipenem against Gram-negative and Gram-positive bacteria, focusing on uropathogens. Five resources (Google [...] Read more.
Tebipenem is a new carbapenem antibiotic that binds to penicillin-binding proteins (PBPs). Given the need for effective antibiotics against multidrug-resistant (MDR) bacteria, this review evaluated the in vitro antimicrobial activity of tebipenem against Gram-negative and Gram-positive bacteria, focusing on uropathogens. Five resources (Google Scholar, Web of Science, Embase, Scopus, and PubMed) were used to identify relevant articles. Of the 1322 articles identified, 9 relevant studies were included, which evaluated 12,501 Gram-negative and 122 Gram-positive pathogens. All nine studies (100%) assessed the activity of tebipenem against Escherichia coli, with an MIC90 value range of 0.015–>4 mg/L. Seven studies (77.8%) included Klebsiella pneumoniae, with an MIC90 value range of 0.015–0.5 mg/L. Six studies (66.7%) reported data on Proteus mirabilis, with an MIC90 value range of ≤0.125–0.5 mg/L. Two studies (22.2%) evaluated the activity of tebipenem against Enterococcus faecalis, with MIC90 of 1 mg/L among vancomycin-susceptible isolates and 32 mg/L in isolates with not-reported mechanisms of resistance. Two studies (22.2%) evaluated the activity of tebipenem against Enterococcus faecium, with MIC90 of >4 mg/L among both vancomycin-susceptible and vancomycin-resistant isolates and MIC90 of 128 mg/L among isolates with no resistance mechanism reported. Tebipenem demonstrated good activity against Enterobacterales, such as E. coli and K. pneumoniae. The antimicrobial agent exhibited higher MICs and a higher proportion of resistance among P. mirabilis isolates. Tebipenem could be effective for outpatient treatment of infections caused by MDR Gram-negative pathogens. However, given its potential to exert selective pressure for the development of antimicrobial resistance, it should be considered for patients with cUTIs when none of the first-line treatment options demonstrate in vitro antimicrobial activity. Full article
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21 pages, 3414 KB  
Article
Spectroscopic and Physicochemical Analysis of Bioactive Cobalt(II) β-Diketo Ester Complexes: Insights into DNA and BSA Binding Mechanisms
by Ignjat Filipović, Snežana Stojanović, Jelena Petronijević, Milena Milutinović, Danijela Nikodijević, Nevena Petrović, Marijana Kosanić and Nenad Joksimović
Analytica 2026, 7(1), 3; https://doi.org/10.3390/analytica7010003 - 29 Dec 2025
Cited by 2 | Viewed by 1465
Abstract
The urgent need for effective therapies against cancer and antimicrobial-resistant pathogens motivates the development of novel metal-based complexes. Herein, we report the synthesis and characterization of four novel cobalt(II) complexes with biologically relevant β-diketo ester ligands. The complexes were characterized via UV-Vis, FTIR, [...] Read more.
The urgent need for effective therapies against cancer and antimicrobial-resistant pathogens motivates the development of novel metal-based complexes. Herein, we report the synthesis and characterization of four novel cobalt(II) complexes with biologically relevant β-diketo ester ligands. The complexes were characterized via UV-Vis, FTIR, mass spectrometry, and elemental analysis. Their biological activities were evaluated through antimicrobial and cytotoxic assays. Complex B1 exhibited the strongest antimicrobial activity, with minimum inhibitory concentrations (MICs) of 0.23 mg/mL against Staphylococcus aureus and Proteus mirabilis, and 0.01 mg/mL against Mucor mucedo, exceeding the performance of ketoconazole. Cytotoxicity studies on SW480 colorectal cancer cells and HaCaT normal keratinocytes identified B3 as the most potent anticancer agent (IC50 = 11.49 µM), selectively targeting tumor cells. Morphological analysis indicated apoptosis as the primary mode of cell death. Mechanistic studies were performed to elucidate interactions with biomolecules. UV-Vis and fluorescence spectroscopy, viscosity measurements, and molecular docking revealed that B3 binds strongly to calf thymus DNA via hydrophobic interactions and groove binding, and exhibits selective binding to bovine serum albumin (site II, subdomain IIIA). These results highlight the potential of cobalt(II) complexes as multifunctional agents with significant antimicrobial and antitumor activities and provide detailed insight into their molecular interactions with DNA and serum proteins. Full article
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17 pages, 1578 KB  
Article
Tranexamic Acid-Phenol Smart Scaffolds with Imine Linker: Unlocking Antimicrobial Potential Through In Vitro and In Silico Insights
by Jovana S. Dragojević, Žiko Milanović, Kristina Milisavljević, Nevena Petrović, Jelena Petronijević, Nenad Joksimović, Vera M. Divac, Marijana Kosanić and Marina D. Kostić
Organics 2025, 6(4), 54; https://doi.org/10.3390/org6040054 - 16 Dec 2025
Cited by 2 | Viewed by 1513
Abstract
A novel series of Schiff bases (3a3k), incorporating tranexamic acid (TXA) and phenol-derived aldehydes via imine linkers, was synthesized and structurally characterized. The antimicrobial activity of the compounds was evaluated against a range of clinically and environmentally relevant bacterial [...] Read more.
A novel series of Schiff bases (3a3k), incorporating tranexamic acid (TXA) and phenol-derived aldehydes via imine linkers, was synthesized and structurally characterized. The antimicrobial activity of the compounds was evaluated against a range of clinically and environmentally relevant bacterial and fungal strains. Among them, derivatives 3i and 3k, bearing bromine and chlorine substituents on the phenol ring, exhibited the most potent antimicrobial effects, particularly against Penicillium italicum and Proteus mirabilis (MIC as low as 0.014 mg/mL). To elucidate the underlying mechanism of action, in silico molecular docking studies were conducted, revealing strong binding affinities of 3i and 3k toward fungal sterol 14α-demethylase (CYP51B), with predicted binding energies surpassing those of the reference antifungal ketoconazole. Additionally, UV-Vis and fluorescence spectroscopy assays demonstrated good stability of compound 3k in PBS and its effective binding to human serum albumin (HSA), respectively. ADMET and ProTox-II predictions further supported the drug-likeness, low toxicity (Class 4), and favorable pharmacokinetic profile of compound 3k. Collectively, these findings highlight TXA–phenol imine derivatives as promising scaffolds for the development of next-generation antimicrobial agents, particularly targeting resistant fungal pathogens. Full article
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47 pages, 10263 KB  
Article
Effectiveness of Chitosan and Its Nanoparticles Against ampC- and ESBL-Producing Pan-Drug-Resistant Proteus mirabilis in Egyptian Livestock
by Ibtisam Faeq Hasona, Amal Awad, Gamal Younis and Wafaa Farouk Mohamed
Pathogens 2025, 14(11), 1176; https://doi.org/10.3390/pathogens14111176 - 18 Nov 2025
Cited by 2 | Viewed by 1537
Abstract
Proteus mirabilis (P. mirabilis) serves as a multi-host–pathogen regarded as an alarming foodborne infectious disease, causing illnesses of variable severity in both livestock and human beings. The present study aimed to estimate the prevalence, antibiotic susceptibility profiles, and associated antimicrobial resistance [...] Read more.
Proteus mirabilis (P. mirabilis) serves as a multi-host–pathogen regarded as an alarming foodborne infectious disease, causing illnesses of variable severity in both livestock and human beings. The present study aimed to estimate the prevalence, antibiotic susceptibility profiles, and associated antimicrobial resistance genes (ARGs) of P. mirabilis isolates obtained from diseased broiler chickens and native Egyptian buffaloes in Kafr El-Sheikh and Dakahlia governorates, Egypt. In addition, this study investigated the antibacterial activity of chitosan (CS) and chitosan nanoparticles (CSNPs), including the estimation of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CS at concentrations of 1% and 2%, as well as CSNPs. Furthermore, the sub-MIC values were utilized to assess the inhibitory effects of CS and CSNPs on swarming motility. P. mirabilis was detected in 68% (34/50) of broiler chickens and 40.74% (11/27) of buffaloes. Interestingly, all P. mirabilis isolates were tested against 21 antimicrobial drugs and showed high resistance against either critical, highly important, or important antimicrobial drugs. For chicken-originated P. mirabilis, 50% (17/34) of isolates were revealed to be extensively drug-resistant (XDR) and 50% (17/34) of isolates were revealed to be pan-drug-resistant (PDR). Meanwhile, 9.09% (1/11) of buffalo-originated P. mirabilis isolates were revealed to be XDR and 90.91% (10/11) of the isolates were revealed to be PDR. Among P. mirabilis isolates from broiler chickens, the prevalence of resistance genes was as follows: int1 (97.06%), dfrA1 (100%), sul2 (97.06%), catA1 (44.12%), aadA1 (97.06%), tet(M) (81.82%), ermB (23.53%), msrA (0%), qnrA (47.06%), qnrS (0%), gyrA (0%), mcr-1 (11.76%), blaTEM (97.06%), blaCTX-M (26.47%), blaOXA-10 (2.94%), blaCMY-2 (41.18%), and blaSHV (0%). The corresponding detection rates in buffalo-derived isolates were 100%, 100%, 90.91%, 63.64%, 100%, 70.59%, 18.18%, 0%, 9.09%, 0%, 0%, 18.18%, 81.82%, 18.18%, 18.18%, 63.64%, and 0%, respectively. Carbapenemase genes were found in none of the isolates from either species. CSNPs demonstrated superior antibacterial and anti-virulence activity against resistant P. mirabilis. CSNPs exhibited significantly lower MIC (0.067–0.081 mg/mL) and MBC (0.167–0.177 mg/mL) values compared with conventional CS formulations (MIC: 3.25–4.5 mg/mL; MBC: 6.67–9.08 mg/mL) in both broiler and buffalo isolates. In inhibition zone assays, the CSNPs + ciprofloxacin (CIP) combination showed the highest efficacy with a 50–58% increase in the inhibition area. Both CSNPs and CS 2% substantially reduced swarming motility by 45–52%, with CSNPs showing the strongest inhibitory effect. These outcomes highlight how P. mirabilis carries and disseminates antibiotic resistance, presenting serious threats to health policy and livestock. Also, CS or CSNPs, either alone or enhanced with CIP, are effective in vitro against resistant P. mirabilis, which promotes the treatment of Proteus infections to guarantee a bactericidal impact. Full article
(This article belongs to the Special Issue Current Progress on Bacterial Antimicrobial Resistance)
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14 pages, 1339 KB  
Article
Repurposed Drugs and Efflux Pump Inhibitors Against Gram-Negative Urinary Tract Pathogenic Bacteria
by Annamária Kincses, Márta Nové, Jina Asefi and Gabriella Spengler
Antibiotics 2025, 14(10), 988; https://doi.org/10.3390/antibiotics14100988 - 2 Oct 2025
Cited by 4 | Viewed by 1844
Abstract
Background/Objectives: Urinary tract infections (UTIs) represent a major healthcare challenge due to antimicrobial resistance and biofilm formation. Our aim was to evaluate whether repurposed drugs and efflux pump inhibitors (EPIs) could provide alternative strategies by investigating their antibacterial, anti-biofilm, and resistance-modifying properties [...] Read more.
Background/Objectives: Urinary tract infections (UTIs) represent a major healthcare challenge due to antimicrobial resistance and biofilm formation. Our aim was to evaluate whether repurposed drugs and efflux pump inhibitors (EPIs) could provide alternative strategies by investigating their antibacterial, anti-biofilm, and resistance-modifying properties against Gram-negative uropathogens under varying pH conditions. Methods: Clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis were tested. Minimum inhibitory concentrations (MICs) of thioridazine (TZ), promethazine (PMZ), fluoxetine (Fx), sertraline (Sr), phenylalanine arginine β-naphthylamide (PAβN), carbonyl cyanide m-chlorophenyl hydrazone (CCCP), and the glutamine uptake inhibitor V9302 were determined at pH 5–8. Biofilm inhibition was assessed by crystal violet staining, while MIC reduction assays tested antibiotic combinations. Efflux pump inhibition was examined using an ethidium bromide accumulation assay. Results: TZ reduced biofilm formation in sensitive K. pneumoniae at all pH levels and enhanced ciprofloxacin (CIP) activity, whereas PMZ showed a weaker effect, limited mainly to neutral pH. Fx and Sr exhibited pH-dependent anti-biofilm activity, with Fx particularly effective against P. mirabilis at alkaline pH. PAβN consistently decreased biofilm biomass in both sensitive and resistant K. pneumoniae and, at pH 7–8, potentiated CIP activity with a 16-fold MIC reduction in the sensitive strain. CCCP showed pH-dependent activity, with stronger effects under acidic conditions, notably in E. coli and P. mirabilis. V9302 was a potent biofilm inhibitor in K. pneumoniae and resistant E. coli and interfered with efflux activity, showing strong effects in acidic environments. Conclusions: Repurposed drugs and EPIs may be useful as antibiotic adjuvants or biofilm inhibitors in treating resistant UTIs. Full article
(This article belongs to the Special Issue New Inhibitors for Overcoming Antimicrobial Resistance)
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19 pages, 1817 KB  
Article
Urinary Tract Infections in a Single-Center Bulgarian Hospital: Trends in Etiology, Antibiotic Resistance, and the Impact of the COVID-19 Pandemic (2017–2022)
by Milena Yancheva Rupcheva, Kostadin Kostadinov, Yordan Kalchev, Petya Gardzheva, Eli Hristozova, Zoya Rachkovska, Gergana Lengerova, Andreana Angelova, Marianna Murdjeva and Michael M. Petrov
Antibiotics 2025, 14(10), 982; https://doi.org/10.3390/antibiotics14100982 - 30 Sep 2025
Cited by 3 | Viewed by 1691
Abstract
Background: Urinary tract infections (UTIs) are among the most common hospital- and community-acquired infections, creating a substantial healthcare burden due to recurrence, complications, and rising antimicrobial resistance. Accurate diagnosis and timely antimicrobial therapy are essential. This study aimed to identify trends in [...] Read more.
Background: Urinary tract infections (UTIs) are among the most common hospital- and community-acquired infections, creating a substantial healthcare burden due to recurrence, complications, and rising antimicrobial resistance. Accurate diagnosis and timely antimicrobial therapy are essential. This study aimed to identify trends in the etiology, treatment, and resistance patterns of UTIs through a retrospective analysis of urine isolates processed at the Laboratory of Microbiology at University Hospital St. George in Plovdiv, the largest tertiary care and reference microbiology center in Bulgaria, between 2017 and 2022. Materials and Methods: A retrospective single-center study was performed at the hospital’s Microbiology Laboratory. During the study period, 74,417 urine samples from 25,087 hospitalized patients were screened with the HB&L UROQUATTRO system. Positive specimens were cultured on blood agar, Eosin-Methylene Blue, and chromogenic media. Identification was performed using biochemical assays, MALDI-TOF MS, and the Vitek 2 Compact system. Antimicrobial susceptibility testing included disk diffusion, MIC determination, broth microdilution (for colistin), and Vitek 2 Compact, interpreted according to EUCAST standards. Descriptive analysis and temporal resistance trends were evaluated with regression models, and interrupted time-series analysis was applied to assess COVID-19-related effects. Results: Out of 10,177 isolates, Gram-negative bacteria predominated (73%), with Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis as the leading pathogens. Among Gram-positives, Enterococcus faecalis was the most frequent. In the post-COVID-19 period, ESBL production increased in E. coli (34–38%), K. pneumoniae (66–77%), and P. mirabilis (13.5–24%). Carbapenem resistance rose in K. pneumoniae (to 40.6%) and P. aeruginosa (to 24%), while none was detected in E. coli. Colistin resistance increased in K. pneumoniae but remained absent in E. coli and P. aeruginosa. High-level aminoglycoside resistance in E. faecalis was stable (~70%), and vancomycin resistance in E. faecium rose from 4.6% to 8.9%. Conclusions: Both community- and hospital-acquired UTIs in Southeastern Bulgaria are increasingly linked to multidrug-resistant pathogens, particularly ESBL-producing and carbapenem-resistant Enterobacterales. Findings from the region’s largest referral center highlight the urgent need for continuous surveillance, rational antibiotic use, and novel therapeutic approaches. Full article
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21 pages, 613 KB  
Article
Nutritional Composition, Volatile Profiles, and Biological Evaluation of Honeys from Melipona interrupta and Melipona seminigra from Amazonas State, Brazil
by Emilly J. S. P. de Lima, Carlos V. A. da Silva, Fernanda A. S. Rocha, Aline de M. Rodrigues, Samuel C. Costa, Rebeca S. França, Raiana S. Gurgel, Bárbara N. Batista, Patrícia M. Albuquerque, Waldireny R. Gomes, Hector H. F. Koolen and Giovana A. Bataglion
Plants 2025, 14(14), 2106; https://doi.org/10.3390/plants14142106 - 9 Jul 2025
Cited by 1 | Viewed by 2241
Abstract
Honey is a natural product produced by bees from the nectar of plants and has been widely used as a sweetener for centuries. In addition to its traditional use, it is also employed for other purposes due to its biological and nutraceutical properties. [...] Read more.
Honey is a natural product produced by bees from the nectar of plants and has been widely used as a sweetener for centuries. In addition to its traditional use, it is also employed for other purposes due to its biological and nutraceutical properties. Although honey production is mostly associated with bees of the genus Apis, species from other genera, such as Melipona, also produce it, albeit on a smaller scale. The honey produced by these two genera shows significant differences in its composition. Moreover, distinct geographical localizations, which, consequently, have different flora, guide the chemical compositions of these samples. Regarding the Amazon region, the amount of knowledge about the honey samples from Melipona species is still scarce. In this context, the present study aimed to characterize the volatile compositions of honey from Melipona interrupta and Melipona seminigra, as well as from the floral sources available, in addition to evaluating their nutritional aspects, antioxidant activity, and antibacterial activity. The analysis of chemical composition was performed using gas chromatography coupled to mass spectrometry (GC-MS). Antioxidant activity was determined by DPPH and ABTS assays, while antimicrobial activity was tested against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus epidermidis, Enterococcus faecalis, Salmonella enterica, Serratia marcescens, Bacillus subtilis, Candida albicans, Candida tropicalis, and Candida parapsilosis. The results allowed the identification of volatiles present in the honey and floral sources. The samples displayed moderate antioxidant activity and slightly antibacterial activity (MIC) of 75 μg/mL against two bacterial strains tested, demonstrating potential antimicrobial activity. Full article
(This article belongs to the Special Issue Mass Spectrometry-Based Approaches in Natural Products Research)
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14 pages, 3299 KB  
Article
Trends in Antimicrobial Resistance of Canine Otitis Pathogens in the Iberian Peninsula (2010–2021)
by Biel Garcias, Mar Batalla, Anna Vidal, Inma Durán and Laila Darwich
Antibiotics 2025, 14(4), 328; https://doi.org/10.3390/antibiotics14040328 - 21 Mar 2025
Cited by 11 | Viewed by 2802
Abstract
Background: The close relationship between humans and petsraises health concerns due to the potential transmission of antimicrobial-resistant (AMR) bacteria and genes. Bacterial otitis is an emerging health problem in dogs, given its widespread prevalence and impact on animal welfare. Early detection of [...] Read more.
Background: The close relationship between humans and petsraises health concerns due to the potential transmission of antimicrobial-resistant (AMR) bacteria and genes. Bacterial otitis is an emerging health problem in dogs, given its widespread prevalence and impact on animal welfare. Early detection of resistance is vital in veterinary medicine to anticipate future treatment challenges. Objective: This study aimed to determine the prevalence of AMR bacteria involved in 12,498 cases of otitis in dogs from the Iberian Peninsula and the evolution of AMR patterns over an 11-year period. Methods: Data was provided by the Veterinary Medicine Department of a large private diagnostic laboratory in Barcelona. Antimicrobial susceptibility testing was performed using the standard disk diffusion method and minimum inhibitory concentration (MIC) testing. Results: The frequency of the principal bacterial agents was 35% Staphylococcus spp. (principally S. pseudointermedius), 20% Pseudomonas spp. (P. aeruginosa), 13% Streptococcus spp. (S. canis), and 11% Enterobacterales (Escherichia coli and Proteus mirabilis). Antimicrobial susceptibility testing revealed P. aeruginosa (among Gram-negatives) and Enterococcus faecalis (among Gram-positives) as the species with the highest AMR to multiple antimicrobial classes throughout the years. According to the frequency and time evolution of multidrug resistance (MDR), Gram-negative bacteria like P. mirabilis (33%) and E. coli (25%) presented higher MDR rates compared to Gram-positive strains like Corynebacterium (7%) and Enterococcus (5%). The AMR evolution also showed an increase in resistance patterns in Proteus spp. to doxycycline and Streptococcus spp. to amikacin. Conclusions: This information can be useful for clinicians, particularly in this region, to make rational antimicrobial use decisions, especially when empirical treatment is common in companion animal veterinary medicine. In summary, improving treatment guidelines is a key strategy for safeguarding both animal and human health, reinforcing the One Health approach. Full article
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13 pages, 792 KB  
Article
Clonal Dissemination of NDM-Producing Proteus mirabilis in a Teaching Hospital in Sousse, Tunisia
by Nadia Jaidane, Lamia Tilouche, Saoussen Oueslati, Delphine Girlich, Sana Azaiez, Aymeric Jacquemin, Laurent Dortet, Walid Naija, Abdelhalim Trabelsi, Thierry Naas, Wejdene Mansour and Rémy A. Bonnin
Pathogens 2025, 14(3), 298; https://doi.org/10.3390/pathogens14030298 - 20 Mar 2025
Cited by 8 | Viewed by 1975
Abstract
Proteus mirabilis (P. mirabilis) is an opportunistic pathogen involved in urinary tract infections as well as various nosocomial infections. Emerging resistances to beta-lactams in this species complicates potential treatment since it is intrinsically resistant to colistin. Eleven isolates of carbapenem-non-susceptible P. [...] Read more.
Proteus mirabilis (P. mirabilis) is an opportunistic pathogen involved in urinary tract infections as well as various nosocomial infections. Emerging resistances to beta-lactams in this species complicates potential treatment since it is intrinsically resistant to colistin. Eleven isolates of carbapenem-non-susceptible P. mirabilis were identified in Sousse Hospital, Tunisia, from January 2018 to December 2022. MICs were determined and isolates were sequenced to determine their resistomes, sequence types, virulence factors, and their clonal relationships. Susceptibility testing showed that all isolates were resistant to carbapenems, aminoglycosides, fluoroquinolones, chloramphenicol, and the trimethoprim/sulfamethoxazole combination. They remained susceptible to the aztreonam/avibactam combination. All isolates produced NDM-1 carbapenemase and ArmA 16S rRNA methylase. In addition, one isolate co-produced the blaVEB-6 gene. All isolates belonged to ST135, and phylogenetic analysis revealed that they were closely related. This study described the first outbreak of NDM-1-producing P. mirabilis in Tunisia. Full article
(This article belongs to the Section Bacterial Pathogens)
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14 pages, 640 KB  
Article
Inhibitory Effects of Essential Oils and Extracts of the Water-Steam Distillation Residues from Greek Herbs on Adherent Biofilm Formation by Common Pathogens
by Gregoria Mitropoulou, Ioanna Karapantzou, Dimitris Tsimogiannis, Vassiliki Oreopoulou, Veronica Lazăr and Yiannis Kourkoutas
Appl. Sci. 2025, 15(6), 3385; https://doi.org/10.3390/app15063385 - 20 Mar 2025
Cited by 3 | Viewed by 2009
Abstract
Biofilms pose a major challenge to the food industry, as they develop on both biotic and abiotic surfaces and contribute to the persistence of antibiotic-resistant pathogens. This study evaluated the antimicrobial and antibiofilm potential of Satureja thymbra, Thymus capitatus, and Origanum [...] Read more.
Biofilms pose a major challenge to the food industry, as they develop on both biotic and abiotic surfaces and contribute to the persistence of antibiotic-resistant pathogens. This study evaluated the antimicrobial and antibiofilm potential of Satureja thymbra, Thymus capitatus, and Origanum hirtum essential oils (EOs), their main components (thymol, carvacrol, p-cymene, and γ-terpinene), and ethanolic and ethyl acetate extracts of the water-steam distillation residue of T. capitatus (WSTRTc). Minimum Inhibition Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of EOs and WSTRTc extracts ranged from 0.6 to 56.8 mg/mL. The corresponding MIC values of the main components ranged in lower values (0.5–2.4 mg/mL). Minimum Biofilm Inhibition Concentration (MBIC) and Minimum Biofilm Eradication Concentration (MBEC) were also determined. MBIC values for the EOs ranged from 0.6 to 4.7 mg/mL against biofilms of Escherichia coli, Listeria monocytogenes, Proteus mirabilis, and Salmonella Enteritidis. Significant antibiofilm activity at concentrations > 61 mg/mL and > 20 mg/mL was recorded by the ethanolic and ethyl acetate WSTRTc extracts, respectively, but no activity against L. monocytogenes and P. mirabilis biofilms was documented. These findings highlighted the efficacy of EOs and extracts derived from Greek herbs, suggesting their application in the food and pharmaceutical industry as natural antimicrobials and biofilm inhibitors. Full article
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21 pages, 7457 KB  
Article
Biosynthesized ZnO-CuO Nanocomposite for Biofilm Formation of Proteus mirabilisupon LuxS Gene Expression
by Mais Emad. Ahmed, Noor Hamza Faiq, Hayfa Habes Almutairi and Mir Waqas Alam
Inorganics 2025, 13(2), 65; https://doi.org/10.3390/inorganics13020065 - 19 Feb 2025
Cited by 25 | Viewed by 2588
Abstract
Proteus mirabilis has been identified as the third most frequent reason for catheter-associated urinary tract infections. The production of urease significantly enhances the force of catheter blockage caused by biofilm formation. Because biofilms are important virulence factors that make antibiotics less potent, it [...] Read more.
Proteus mirabilis has been identified as the third most frequent reason for catheter-associated urinary tract infections. The production of urease significantly enhances the force of catheter blockage caused by biofilm formation. Because biofilms are important virulence factors that make antibiotics less potent, it is becoming increasingly important to develop novel alternative antibiotics. In addition to the unique properties they possess, nanoparticles made from metal oxide are currently attracting considerable attention as possible antibacterials. This research aims to explore the potential anti-biofilm properties of green manufactured ZnO-CuO nanoparticles generated by P. mirabilis. By synthesizing reductive enzymes, bacterial cells can participate in the biosynthesis process. This study explores whether green synthesized ZnO-CuO nanoparticles can work as an anti-biofilm agent formed by P. mirabilis. These nanoparticles were generated using Bacteriocins to determine their effectiveness against bacteria, which were partially purified and showed antimicrobial activity against Gram-negative bacteria of P. mirabilis. AFM, TEM, FESEM, XRD, and ultraviolet (UV)–visible spectroscopy were used to analyze the biosynthesized nanoparticles to ascertain their chemical and physical characteristics. XRD verified the hexagonal structure, TEM demonstrated a size range of 96.00 nm, and FESEM verified the surface morphology. The dispersion and roughness of the nanoparticles are shown through AFM examination. The produced nanoparticles’ UV-visible spectra displayed a maximum peak at 287 and 232 nm. When applied to strains (wild-type) of Proteus mirabilis (multidrug-resistant), copper and zinc nanoparticles had notable biofilm inhibitory effects. Weak biofilm production has been demonstrated by bacteria that effectively generate biofilms, following incubation with 128 μg/mL subminimum inhibitory concentrations (MICs) of CuO nanoparticles for 24 and 48 h at 37 °C. Following treatment with the ZnO-CuO nanocomposite of these strains, downregulation alterations in LuxS expression were detected by utilizing a real-time PCR process. After this, isolates were treated with the nanocomposite, and downregulated shifts in LuxS expression were found by utilizing the real-time PCR technique in contrast with the isolates that were not treated. Zinc oxide (ZnO) nanoparticles can be utilized as antibacterial agents in a concentration-dependent manner, aligning with all observed findings. The present research demonstrates that green synthesized copper oxide–zinc oxide nanocomposites are effective anti-biofilm agents against P. mirabilis. Their noteworthy downregulation of LuxS gene expression successfully prevents biofilm formation and swarming motility. Full article
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20 pages, 4160 KB  
Article
Chemical Composition, Antibacterial Activity, and Food Application of Sprouts from Fabaceae and Brassicaceae Species
by Christine (Neagu) Dragomir, Corina Dana Misca, Sylvestre Dossa, Călin Jianu, Isidora Radulov, Monica Negrea, Loredana Paven and Ersilia Alexa
Appl. Sci. 2025, 15(4), 1896; https://doi.org/10.3390/app15041896 - 12 Feb 2025
Cited by 9 | Viewed by 2429
Abstract
The aim of this paper is to evaluate, from a chemical and antibacterial point of view, sprouts from species of Fabaceae and Brassicaceae families, to establish a correlation between analyzed parameters and to test the possibility of using these functional compounds in the [...] Read more.
The aim of this paper is to evaluate, from a chemical and antibacterial point of view, sprouts from species of Fabaceae and Brassicaceae families, to establish a correlation between analyzed parameters and to test the possibility of using these functional compounds in the flour food industry. The material used was lentil sprouts (LS), pea sprouts (PS), bean sprouts (BS), and radish sprouts (RS), which were chemically analyzed by determining the content of total and individual polyphenols and macro- and microelements. The antimicrobial potential of the sprout extracts obtained was tested using the disk diffusion method on five bacterial strains: Escherichia coli, Proteus mirabilis, Klebsiella pneumoniae, Enterococcus faecalis, and Staphylococcus aureus. In order to capitalize on the flour food industry, the sprouts were introduced in the recipes for the manufacture of some cookies, and sensory analysis was performed. The results obtained indicated that LS are the sprouts with the highest content of TPC (524.130 mg/100 g) and highest content for Ni, Cu, Zn, Fe, Mn, and Mg, while the highest values for Ca were recorded in the case of PS (256.575 ± 2.23 mg/kg), and for K in the case of the BS sample (4819.450 ± 1.1 mg/kg). The RS extract has been shown to be effective against E. faecalis (MIC-70 µL/mL), S. aureus (MIC 50 µL/mL), and PS against S. aureus (MIC 70 µL/mL). Regarding the sensory analysis of cookies, the panelists participating in the study preferred products based on BS and PS in a percentage of 2.5%. Full article
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